I would rely on storing bottled water before trying to desalinate salt water. My suggestion is to try your chosen method before you need it and see if it really works.

http://www.watercone.com/product.html
http://www.freedrinkingwater.com/ro-counter-detail.htm

As an aside, I've traveled to an island which produces its water by desalination. The inhabitants know that the water is _potable_, but they don't consider it _drinkable_. They all buy bottled water.

Phil